The present invention relates to silicone hydrogel contact lenses and the production thereof. More particularly, the present invention relates to systems and methods for producing silicone hydrogel contact lenses.
Soft contact lenses can be produced in plastic contact lens mold assemblies by polymerizing lens precursor compositions in the contact lens mold assemblies. Existing contact lens mold assemblies comprise a first mold section and a second mold section. Each mold section has a single surface that corresponds to a surface of a soft contact lens having an optically acceptable quality. When mold sections formed from polypropylene or other similar materials are used to form mold assemblies, the assemblies are formed from an interference fit between the first and second mold sections.
A lens precursor composition contained in the mold assembly can be polymerized to form a contact lens located in a lens shaped cavity of the mold assembly. For example, a lens precursor composition can be exposed to ultraviolet light to polymerize the composition. The light delivered to the lens precursor composition is usually not uniformly or constantly applied to the mold assemblies since light-emitting lamps are located on only one side of the mold assemblies. To address this issue, the light emitted from the lamps is delivered at high intensities. However, the light is still not uniform or constant.
After polymerizing the lens precursor composition, the mold sections are separated by breaking the interference fit between the two mold sections. Unreacted monomers and the like can be extracted, and the lens can be packaged. For silicone hydrogel contact lenses, the extraction process often requires the lens to be contacted with an organic solvent. After a period of time, when the solvent has become contaminated with the unreacted monomers, the solvent is discarded.
In addition, since a silicone hydrogel contact lens formed in a polypropylene mold or other mold formed from similar materials has surfaces with insufficient wettability characteristics required for ophthalmic use, the silicone hydrogel contact lens undergoes a surface treatment or surface modification to enhance the wettability of the lens surfaces.
Thus, there remains a need for improved systems and methods for producing silicone hydrogel contact lenses that reduce manufacturing time, manufacturing costs, and/or produce large quantities of silicone hydrogel contact lenses that are ophthalmically acceptable and provide vision enhancement with little or no negative side effects.